The purpose of this study is to investigate the effects of mothers’ parenting stress and the difficulties in emotion regulation on mothers’ response to children’s negative emotion expression and to find out whether the difficulties in emotion regulation play a role as a mediator between parenting stress and mothers’ response to children’s negative emotion expression. The participants were 222 mothers between the ages of 21 to 49 with children between the ages of 3-6. The mothers completed three questionnaires, which were the Korean version of the Parenting Stress Index-short Form (K-PSI-SF), the Difficulties in Emotion Regulation Scale (K-DERS) and Coping with Children’s Negative Emotions Scale (CCNES). Data were analyzed by using Cronbach alpha, correlation, regression analysis and the Baron & Kenny(1986) mediating effect validation procedure. The results indicate that the difficulties in emotion regulation partially mediated the relationship between parenting stress and the mothers’ responses to children’s negative emotion expression. This study helped to provide a better understanding of the influence process of parenting stress on the mothers’ supportive and non-supportive response to children’s negative emotion expression by the mediating effects of the difficulties in emotion regulation. Other related implications of these findings and suggestions for future research are also discussed.